Molecular genetic analysis of the RNA-mediated signaling pathways

本研究旨在揭示rna结合蛋白调控的信号转导通路的调控机制。我们利用裂变酵母模型系统和分子遗传学方法鉴定了调节包括MAP激酶途径在内的各种信号通路的RNA结合蛋白。我们鉴定了几种rna结合蛋白，包括编码高度保守的kh型rna结合蛋白的Rncl。Rncl过表达降低了Pmkl MAPK信号的激活，Rncl缺失增加了Pmk1 MAPK信号的磷酸化水平，从而表明Rncl作为Pmkl MAPK信号的负调控因子。我们证明了Rncl结合并稳定了编码MAPK磷酸酶的Pmpl mRNA。此外，Pmk1 MAPK磷酸化Rncl，从而调节Rncl的rna结合活性，从而结合并稳定Pmpl mRNA。我们还发现了编码tRNA脱氨酶突变的tad3-1突变体。值得注意的是，我们证明了tad3-1突变体在G1/S和G2/M转变时表现出细胞周期进程的缺陷，从而表明摇摆tRNA修饰对裂变酵母的细胞周期至关重要。我们还发现了一种rrm型RNA结合蛋白，它可以稳定编码肌动蛋白结合蛋白的mRNA。值得注意的是，MAPK Pmk1直接磷酸化rrm型rna结合蛋白，这种磷酸化负调控rna结合蛋白结合靶mrna的活性。长期以来，MAPK通路一直被认为是通过磷酸化各种转录因子来调节细胞信号的转录调节因子。我们的数据提出了一种涉及mapk介导的转录后rna代谢调节的新范式。

This research aims to unravel the regulatory mechanisms of the signal transduction pathway regulated by RNA-binding proteins. We utilized the fission yeast model system and molecular genetic approach to identify RNA binding proteins that regulate various signaling pathways including MAP kinase pathways. We identified several RNA-binding proteins including Rncl that encodes a highly conserved KH-type RNA-binding protein. Rncl overexpression decreased the activation of the Pmkl MAPK signaling and Rncl deletion increased the phosphorylation level of the Pmk1 MAPK signaling thus indicating that Rncl acts as a negative regulator of the Pmkl MAPK signaling. We demonstrated that Rncl binds and stabilizes Pmpl mRNA that encodes a MAPK phosphatase for Pmkl MAPK Moreover, Pmk1 MAPK phosphorylates Rncl which regulates the RNA-binding activity of Rncl to bind and stabilize Pmpl mRNA. We also identified the tad3-1 mutant that encodes a mutation in the tRNA deaminase. Notably, we demonstrated that the tad3-1 mutants displayed defects in cell cycle progression at G1/S and G2/M transitions thus indicating that the wobble tRNA modification is essential to cell cycle in fission yeast. We also identified an RRM-type RNA binding protein that stabilizes the mRNA encoding an actin-binding protein. Notably, the MAPK Pmk1 directly phosphorylates the RRM-type RNA-binding protein and this phosphorylation negatively regulates the activity of the RNA-binding protein to bind target mRNAs. The MAPK pathways have long been known as a transcriptional regulator of cellular signaling by phosphorylating various transcription factors. Our data suggest a novel paradigm involving the MAPK-mediated regulation of the post-transcriptional RNAmetabolism.